/******************************************************
Database log

(c) 1995 Innobase Oy

Created 12/9/1995 Heikki Tuuri
*******************************************************/

#ifndef log0log_h
#define log0log_h

#include "univ.i"
#include "ut0byte.h"
#include "sync0sync.h"
#include "sync0rw.h"

typedef struct log_struct log_t;
typedef struct log_group_struct log_group_t;

#ifdef UNIV_DEBUG
extern ibool log_do_write;
extern ibool log_debug_writes;
#else /* UNIV_DEBUG */
#define log_do_write TRUE
#endif /* UNIV_DEBUG */

/* Wait modes for log_write_up_to */
#define LOG_NO_WAIT 91
#define LOG_WAIT_ONE_GROUP 92
#define LOG_WAIT_ALL_GROUPS 93
#define LOG_MAX_N_GROUPS 32

/********************************************************************
Sets the global variable log_fsp_current_free_limit. Also makes a checkpoint,
so that we know that the limit has been written to a log checkpoint field
on disk. */

void log_fsp_current_free_limit_set_and_checkpoint(
    /*==========================================*/
    ulint limit); /* in: limit to set */
/***********************************************************************
Calculates where in log files we find a specified lsn. */

ulint log_calc_where_lsn_is(
    /*==================*/
    /* out: log file number */
    ib_longlong *log_file_offset, /* out: offset in that file
                                  (including the header) */
    dulint first_header_lsn,      /* in: first log file start
                                  lsn */
    dulint lsn,                   /* in: lsn whose position to
                                  determine */
    ulint n_log_files,            /* in: total number of log
                                  files */
    ib_longlong log_file_size);   /* in: log file size
                                  (including the header) */
/****************************************************************
Writes to the log the string given. The log must be released with
log_release. */
UNIV_INLINE
dulint log_reserve_and_write_fast(
    /*=======================*/
    /* out: end lsn of the log record, ut_dulint_zero if
    did not succeed */
    byte *str,         /* in: string */
    ulint len,         /* in: string length */
    dulint *start_lsn, /* out: start lsn of the log record */
    ibool *success);   /* out: TRUE if success */
/***************************************************************************
Releases the log mutex. */
UNIV_INLINE
void log_release(void);
/*=============*/
/***************************************************************************
Checks if there is need for a log buffer flush or a new checkpoint, and does
this if yes. Any database operation should call this when it has modified
more than about 4 pages. NOTE that this function may only be called when the
OS thread owns no synchronization objects except the dictionary mutex. */
UNIV_INLINE
void log_free_check(void);
/*================*/
/****************************************************************
Opens the log for log_write_low. The log must be closed with log_close and
released with log_release. */

dulint log_reserve_and_open(
    /*=================*/
    /* out: start lsn of the log record */
    ulint len); /* in: length of data to be catenated */
/****************************************************************
Writes to the log the string given. It is assumed that the caller holds the
log mutex. */

void log_write_low(
    /*==========*/
    byte *str,      /* in: string */
    ulint str_len); /* in: string length */
/****************************************************************
Closes the log. */

dulint log_close(void);
/*===========*/
/* out: lsn */
/****************************************************************
Gets the current lsn. */
UNIV_INLINE
dulint log_get_lsn(void);
/*=============*/
/* out: current lsn */
/**********************************************************
Initializes the log. */

void log_init(void);
/*==========*/
/**********************************************************************
Inits a log group to the log system. */

void log_group_init(
    /*===========*/
    ulint id,                /* in: group id */
    ulint n_files,           /* in: number of log files */
    ulint file_size,         /* in: log file size in bytes */
    ulint space_id,          /* in: space id of the file space
                             which contains the log files of this
                             group */
    ulint archive_space_id); /* in: space id of the file space
                             which contains some archived log
                             files for this group; currently, only
                             for the first log group this is
                             used */
/**********************************************************
Completes an i/o to a log file. */

void log_io_complete(
    /*============*/
    log_group_t *group); /* in: log group */
/**********************************************************
This function is called, e.g., when a transaction wants to commit. It checks
that the log has been written to the log file up to the last log entry written
by the transaction. If there is a flush running, it waits and checks if the
flush flushed enough. If not, starts a new flush. */

void log_write_up_to(
    /*============*/
    dulint lsn, /* in: log sequence number up to which the log should
                be written, ut_dulint_max if not specified */
    ulint wait, /* in: LOG_NO_WAIT, LOG_WAIT_ONE_GROUP,
                or LOG_WAIT_ALL_GROUPS */
    ibool flush_to_disk);
/* in: TRUE if we want the written log also to be
flushed to disk */
/********************************************************************
Does a syncronous flush of the log buffer to disk. */

void log_buffer_flush_to_disk(void);
/*==========================*/
/********************************************************************
Advances the smallest lsn for which there are unflushed dirty blocks in the
buffer pool and also may make a new checkpoint. NOTE: this function may only
be called if the calling thread owns no synchronization objects! */

ibool log_preflush_pool_modified_pages(
    /*=============================*/
    /* out: FALSE if there was a flush batch of
    the same type running, which means that we
    could not start this flush batch */
    dulint new_oldest, /* in: try to advance oldest_modified_lsn
                       at least to this lsn */
    ibool sync);       /* in: TRUE if synchronous operation is
                       desired */
/**********************************************************
Makes a checkpoint. Note that this function does not flush dirty
blocks from the buffer pool: it only checks what is lsn of the oldest
modification in the pool, and writes information about the lsn in
log files. Use log_make_checkpoint_at to flush also the pool. */

ibool log_checkpoint(
    /*===========*/
    /* out: TRUE if success, FALSE if a checkpoint
    write was already running */
    ibool sync,          /* in: TRUE if synchronous operation is
                         desired */
    ibool write_always); /* in: the function normally checks if the
                         the new checkpoint would have a greater
                         lsn than the previous one: if not, then no
                         physical write is done; by setting this
                         parameter TRUE, a physical write will always be
                         made to log files */
/********************************************************************
Makes a checkpoint at a given lsn or later. */

void log_make_checkpoint_at(
    /*===================*/
    dulint lsn,          /* in: make a checkpoint at this or a later
                         lsn, if ut_dulint_max, makes a checkpoint at
                         the latest lsn */
    ibool write_always); /* in: the function normally checks if the
                         the new checkpoint would have a greater
                         lsn than the previous one: if not, then no
                         physical write is done; by setting this
                         parameter TRUE, a physical write will always be
                         made to log files */
/********************************************************************
Makes a checkpoint at the latest lsn and writes it to first page of each
data file in the database, so that we know that the file spaces contain
all modifications up to that lsn. This can only be called at database
shutdown. This function also writes all log in log files to the log archive. */

void logs_empty_and_mark_files_at_shutdown(void);
/*=======================================*/
/**********************************************************
Reads a checkpoint info from a log group header to log_sys->checkpoint_buf. */

void log_group_read_checkpoint_info(
    /*===========================*/
    log_group_t *group, /* in: log group */
    ulint field);       /* in: LOG_CHECKPOINT_1 or LOG_CHECKPOINT_2 */
/***********************************************************************
Gets info from a checkpoint about a log group. */

void log_checkpoint_get_nth_group_info(
    /*==============================*/
    byte *buf,      /* in: buffer containing checkpoint info */
    ulint n,        /* in: nth slot */
    ulint *file_no, /* out: archived file number */
    ulint *offset); /* out: archived file offset */
/**********************************************************
Writes checkpoint info to groups. */

void log_groups_write_checkpoint_info(void);
/*==================================*/
/**********************************************************
Writes info to a buffer of a log group when log files are created in
backup restoration. */

void log_reset_first_header_and_checkpoint(
    /*==================================*/
    byte *hdr_buf, /* in: buffer which will be written to the start
                   of the first log file */
    dulint start); /* in: lsn of the start of the first log file;
                   we pretend that there is a checkpoint at
                   start + LOG_BLOCK_HDR_SIZE */
/************************************************************************
Starts an archiving operation. */

ibool log_archive_do(
    /*===========*/
    /* out: TRUE if succeed, FALSE if an archiving
    operation was already running */
    ibool sync,      /* in: TRUE if synchronous operation is desired */
    ulint *n_bytes); /* out: archive log buffer size, 0 if nothing to
                    archive */
/********************************************************************
Writes the log contents to the archive up to the lsn when this function was
called, and stops the archiving. When archiving is started again, the archived
log file numbers start from a number one higher, so that the archiving will
not write again to the archived log files which exist when this function
returns. */

ulint log_archive_stop(void);
/*==================*/
/* out: DB_SUCCESS or DB_ERROR */
/********************************************************************
Starts again archiving which has been stopped. */

ulint log_archive_start(void);
/*===================*/
/* out: DB_SUCCESS or DB_ERROR */
/********************************************************************
Stop archiving the log so that a gap may occur in the archived log files. */

ulint log_archive_noarchivelog(void);
/*==========================*/
/* out: DB_SUCCESS or DB_ERROR */
/********************************************************************
Start archiving the log so that a gap may occur in the archived log files. */

ulint log_archive_archivelog(void);
/*========================*/
/* out: DB_SUCCESS or DB_ERROR */
/**********************************************************
Generates an archived log file name. */

void log_archived_file_name_gen(
    /*=======================*/
    char *buf,      /* in: buffer where to write */
    ulint id,       /* in: group id */
    ulint file_no); /* in: file number */
/************************************************************************
Checks that there is enough free space in the log to start a new query step.
Flushes the log buffer or makes a new checkpoint if necessary. NOTE: this
function may only be called if the calling thread owns no synchronization
objects! */

void log_check_margins(void);
/*===================*/
/**********************************************************
Reads a specified log segment to a buffer. */

void log_group_read_log_seg(
    /*===================*/
    ulint type,         /* in: LOG_ARCHIVE or LOG_RECOVER */
    byte *buf,          /* in: buffer where to read */
    log_group_t *group, /* in: log group */
    dulint start_lsn,   /* in: read area start */
    dulint end_lsn);    /* in: read area end */
/**********************************************************
Writes a buffer to a log file group. */

void log_group_write_buf(
    /*================*/
    log_group_t *group,     /* in: log group */
    byte *buf,              /* in: buffer */
    ulint len,              /* in: buffer len; must be divisible
                            by OS_FILE_LOG_BLOCK_SIZE */
    dulint start_lsn,       /* in: start lsn of the buffer; must
                            be divisible by
                            OS_FILE_LOG_BLOCK_SIZE */
    ulint new_data_offset); /* in: start offset of new data in
                           buf: this parameter is used to decide
                           if we have to write a new log file
                           header */
/************************************************************
Sets the field values in group to correspond to a given lsn. For this function
to work, the values must already be correctly initialized to correspond to
some lsn, for instance, a checkpoint lsn. */

void log_group_set_fields(
    /*=================*/
    log_group_t *group, /* in: group */
    dulint lsn);        /* in: lsn for which the values should be
                        set */
/**********************************************************
Calculates the data capacity of a log group, when the log file headers are not
included. */

ulint log_group_get_capacity(
    /*===================*/
    /* out: capacity in bytes */
    log_group_t *group); /* in: log group */
/****************************************************************
Gets a log block flush bit. */
UNIV_INLINE
ibool log_block_get_flush_bit(
    /*====================*/
    /* out: TRUE if this block was the first
    to be written in a log flush */
    byte *log_block); /* in: log block */
/****************************************************************
Gets a log block number stored in the header. */
UNIV_INLINE
ulint log_block_get_hdr_no(
    /*=================*/
    /* out: log block number stored in the block
    header */
    byte *log_block); /* in: log block */
/****************************************************************
Gets a log block data length. */
UNIV_INLINE
ulint log_block_get_data_len(
    /*===================*/
    /* out: log block data length measured as a
    byte offset from the block start */
    byte *log_block); /* in: log block */
/****************************************************************
Sets the log block data length. */
UNIV_INLINE
void log_block_set_data_len(
    /*===================*/
    byte *log_block, /* in: log block */
    ulint len);      /* in: data length */
/****************************************************************
Calculates the checksum for a log block. */
UNIV_INLINE
ulint log_block_calc_checksum(
    /*====================*/
    /* out: checksum */
    byte *block); /* in: log block */
/****************************************************************
Gets a log block checksum field value. */
UNIV_INLINE
ulint log_block_get_checksum(
    /*===================*/
    /* out: checksum */
    byte *log_block); /* in: log block */
/****************************************************************
Sets a log block checksum field value. */
UNIV_INLINE
void log_block_set_checksum(
    /*===================*/
    byte *log_block, /* in: log block */
    ulint checksum); /* in: checksum */
/****************************************************************
Gets a log block first mtr log record group offset. */
UNIV_INLINE
ulint log_block_get_first_rec_group(
    /*==========================*/
    /* out: first mtr log record group byte offset
    from the block start, 0 if none */
    byte *log_block); /* in: log block */
/****************************************************************
Sets the log block first mtr log record group offset. */
UNIV_INLINE
void log_block_set_first_rec_group(
    /*==========================*/
    byte *log_block, /* in: log block */
    ulint offset);   /* in: offset, 0 if none */
/****************************************************************
Gets a log block checkpoint number field (4 lowest bytes). */
UNIV_INLINE
ulint log_block_get_checkpoint_no(
    /*========================*/
    /* out: checkpoint no (4 lowest bytes) */
    byte *log_block); /* in: log block */
/****************************************************************
Initializes a log block in the log buffer. */
UNIV_INLINE
void log_block_init(
    /*===========*/
    byte *log_block, /* in: pointer to the log buffer */
    dulint lsn);     /* in: lsn within the log block */
/****************************************************************
Initializes a log block in the log buffer in the old, < 3.23.52 format, where
there was no checksum yet. */
UNIV_INLINE
void log_block_init_in_old_format(
    /*=========================*/
    byte *log_block, /* in: pointer to the log buffer */
    dulint lsn);     /* in: lsn within the log block */
/****************************************************************
Converts a lsn to a log block number. */
UNIV_INLINE
ulint log_block_convert_lsn_to_no(
    /*========================*/
    /* out: log block number, it is > 0 and <= 1G */
    dulint lsn); /* in: lsn of a byte within the block */
/**********************************************************
Prints info of the log. */

void log_print(
    /*======*/
    FILE *file); /* in: file where to print */
/**********************************************************
Peeks the current lsn. */

ibool log_peek_lsn(
    /*=========*/
    /* out: TRUE if success, FALSE if could not get the
    log system mutex */
    dulint *lsn); /* out: if returns TRUE, current lsn is here */
/**************************************************************************
Refreshes the statistics used to print per-second averages. */

void log_refresh_stats(void);
/*===================*/

extern log_t *log_sys;

/* Values used as flags */
#define LOG_FLUSH 7652559
#define LOG_CHECKPOINT 78656949
#define LOG_ARCHIVE 11122331
#define LOG_RECOVER 98887331

/* The counting of lsn's starts from this value: this must be non-zero */
#define LOG_START_LSN ut_dulint_create(0, 16 * OS_FILE_LOG_BLOCK_SIZE)

#define LOG_BUFFER_SIZE (srv_log_buffer_size * UNIV_PAGE_SIZE)
#define LOG_ARCHIVE_BUF_SIZE (srv_log_buffer_size * UNIV_PAGE_SIZE / 4)

/* Offsets of a log block header */
#define LOG_BLOCK_HDR_NO                   \
  0 /* block number which must be > 0 and  \
    is allowed to wrap around at 2G; the   \
    highest bit is set to 1 if this is the \
    first log block in a log flush write   \
    segment */
#define LOG_BLOCK_FLUSH_BIT_MASK 0x80000000UL
/* mask used to get the highest bit in
the preceding field */
#define LOG_BLOCK_HDR_DATA_LEN           \
  4 /* number of bytes of log written to \
    this block */
#define LOG_BLOCK_FIRST_REC_GROUP           \
  6 /* offset of the first start of an      \
    mtr log record group in this log block, \
    0 if none; if the value is the same     \
    as LOG_BLOCK_HDR_DATA_LEN, it means     \
    that the first rec group has not yet    \
    been catenated to this log block, but   \
    if it will, it will start at this       \
    offset; an archive recovery can         \
    start parsing the log records starting  \
    from this offset in this log block,     \
    if value not 0 */
#define LOG_BLOCK_CHECKPOINT_NO           \
  8 /* 4 lower bytes of the value of      \
    log_sys->next_checkpoint_no when the  \
    log block was last written to: if the \
    block has not yet been written full,  \
    this value is only updated before a   \
    log buffer flush */
#define LOG_BLOCK_HDR_SIZE              \
  12 /* size of the log block header in \
     bytes */

/* Offsets of a log block trailer from the end of the block */
#define LOG_BLOCK_CHECKSUM                                       \
  4                          /* 4 byte checksum of the log block \
                             contents; in InnoDB versions        \
                             < 3.23.52 this did not contain the  \
                             checksum but the same value as      \
                             .._HDR_NO */
#define LOG_BLOCK_TRL_SIZE 4 /* trailer size in bytes */

/* Offsets for a checkpoint field */
#define LOG_CHECKPOINT_NO 0
#define LOG_CHECKPOINT_LSN 8
#define LOG_CHECKPOINT_OFFSET 16
#define LOG_CHECKPOINT_LOG_BUF_SIZE 20
#define LOG_CHECKPOINT_ARCHIVED_LSN 24
#define LOG_CHECKPOINT_GROUP_ARRAY 32

/* For each value < LOG_MAX_N_GROUPS the following 8 bytes: */

#define LOG_CHECKPOINT_ARCHIVED_FILE_NO 0
#define LOG_CHECKPOINT_ARCHIVED_OFFSET 4

#define LOG_CHECKPOINT_ARRAY_END (LOG_CHECKPOINT_GROUP_ARRAY + LOG_MAX_N_GROUPS * 8)
#define LOG_CHECKPOINT_CHECKSUM_1 LOG_CHECKPOINT_ARRAY_END
#define LOG_CHECKPOINT_CHECKSUM_2 (4 + LOG_CHECKPOINT_ARRAY_END)
#define LOG_CHECKPOINT_FSP_FREE_LIMIT (8 + LOG_CHECKPOINT_ARRAY_END)
/* current fsp free limit in
tablespace 0, in units of one
megabyte; this information is only used
by ibbackup to decide if it can
truncate unused ends of
non-auto-extending data files in space
0 */
#define LOG_CHECKPOINT_FSP_MAGIC_N (12 + LOG_CHECKPOINT_ARRAY_END)
/* this magic number tells if the
checkpoint contains the above field:
the field was added to
InnoDB-3.23.50 */
#define LOG_CHECKPOINT_SIZE (16 + LOG_CHECKPOINT_ARRAY_END)

#define LOG_CHECKPOINT_FSP_MAGIC_N_VAL 1441231243

/* Offsets of a log file header */
#define LOG_GROUP_ID 0 /* log group number */
#define LOG_FILE_START_LSN              \
  4 /* lsn of the start of data in this \
    log file */
#define LOG_FILE_NO                      \
  12 /* 4-byte archived log file number; \
     this field is only defined in an    \
     archived log file */
#define LOG_FILE_WAS_CREATED_BY_HOT_BACKUP 16
/* a 32-byte field which contains
the string 'ibbackup' and the
creation time if the log file was
created by ibbackup --restore;
when mysqld is first time started
on the restored database, it can
print helpful info for the user */
#define LOG_FILE_ARCH_COMPLETED OS_FILE_LOG_BLOCK_SIZE
/* this 4-byte field is TRUE when
the writing of an archived log file
has been completed; this field is
only defined in an archived log file */
#define LOG_FILE_END_LSN (OS_FILE_LOG_BLOCK_SIZE + 4)
/* lsn where the archived log file
at least extends: actually the
archived log file may extend to a
later lsn, as long as it is within the
same log block as this lsn; this field
is defined only when an archived log
file has been completely written */
#define LOG_CHECKPOINT_1 OS_FILE_LOG_BLOCK_SIZE
/* first checkpoint field in the log
header; we write alternately to the
checkpoint fields when we make new
checkpoints; this field is only defined
in the first log file of a log group */
#define LOG_CHECKPOINT_2 (3 * OS_FILE_LOG_BLOCK_SIZE)
/* second checkpoint field in the log
header */
#define LOG_FILE_HDR_SIZE (4 * OS_FILE_LOG_BLOCK_SIZE)

#define LOG_GROUP_OK 301
#define LOG_GROUP_CORRUPTED 302

/* Log group consists of a number of log files, each of the same size; a log
group is implemented as a space in the sense of the module fil0fil. */

struct log_group_struct
{
  /* The following fields are protected by log_sys->mutex */
  ulint id;                /* log group id */
  ulint n_files;           /* number of files in the group */
  ulint file_size;         /* individual log file size in bytes,
                           including the log file header */
  ulint space_id;          /* file space which implements the log
                           group */
  ulint state;             /* LOG_GROUP_OK or
                           LOG_GROUP_CORRUPTED */
  dulint lsn;              /* lsn used to fix coordinates within
                           the log group */
  ulint lsn_offset;        /* the offset of the above lsn */
  ulint n_pending_writes;  /* number of currently pending flush
                          writes for this log group */
  byte **file_header_bufs; /* buffers for each file header in the
                          group */
  /*-----------------------------*/
  byte **archive_file_header_bufs; /* buffers for each file
                          header in the group */
  ulint archive_space_id;          /* file space which implements the log
                                  group archive */
  ulint archived_file_no;          /* file number corresponding to
                                  log_sys->archived_lsn */
  ulint archived_offset;           /* file offset corresponding to
                                   log_sys->archived_lsn, 0 if we have
                                   not yet written to the archive file
                                   number archived_file_no */
  ulint next_archived_file_no;     /* during an archive write,
                             until the write is completed, we
                             store the next value for
                             archived_file_no here: the write
                             completion function then sets the new
                             value to ..._file_no */
  ulint next_archived_offset;      /* like the preceding field */
  /*-----------------------------*/
  dulint scanned_lsn;   /* used only in recovery: recovery scan
                        succeeded up to this lsn in this log
                        group */
  byte *checkpoint_buf; /* checkpoint header is written from
                        this buffer to the group */
  UT_LIST_NODE_T(log_group_t)
  log_groups; /* list of log groups */
};

struct log_struct
{
  byte pad[64];       /* padding to prevent other memory
                      update hotspots from residing on the
                      same memory cache line */
  dulint lsn;         /* log sequence number */
  ulint buf_free;     /* first free offset within the log
                      buffer */
  mutex_t mutex;      /* mutex protecting the log */
  byte *buf;          /* log buffer */
  ulint buf_size;     /* log buffer size in bytes */
  ulint max_buf_free; /* recommended maximum value of
                      buf_free, after which the buffer is
                      flushed */
  ulint old_buf_free; /* value of buf free when log was
                      last time opened; only in the debug
                      version */
  dulint old_lsn;     /* value of lsn when log was last time
                      opened; only in the debug version */
  ibool check_flush_or_checkpoint;
  /* this is set to TRUE when there may
  be need to flush the log buffer, or
  preflush buffer pool pages, or make
  a checkpoint; this MUST be TRUE when
  lsn - last_checkpoint_lsn >
  max_checkpoint_age; this flag is
  peeked at by log_free_check(), which
  does not reserve the log mutex */
  UT_LIST_BASE_NODE_T(log_group_t)
  log_groups; /* log groups */

  /* The fields involved in the log buffer flush */

  ulint buf_next_to_write; /* first offset in the log buffer
                         where the byte content may not exist
                         written to file, e.g., the start
                         offset of a log record catenated
                         later; this is advanced when a flush
                         operation is completed to all the log
                         groups */
  dulint written_to_some_lsn;
  /* first log sequence number not yet
  written to any log group; for this to
  be advanced, it is enough that the
  write i/o has been completed for any
  one log group */
  dulint written_to_all_lsn;
  /* first log sequence number not yet
  written to some log group; for this to
  be advanced, it is enough that the
  write i/o has been completed for all
  log groups */
  dulint write_lsn;         /* end lsn for the current running
                            write */
  ulint write_end_offset;   /* the data in buffer has been written
                           up to this offset when the current
                           write ends: this field will then
                           be copied to buf_next_to_write */
  dulint current_flush_lsn; /* end lsn for the current running
                          write + flush operation */
  dulint flushed_to_disk_lsn;
  /* how far we have written the log
  AND flushed to disk */
  ulint n_pending_writes; /* number of currently pending flushes
                         or writes */
  /* NOTE on the 'flush' in names of the fields below: starting from
  4.0.14, we separate the write of the log file and the actual fsync()
  or other method to flush it to disk. The names below shhould really
  be 'flush_or_write'! */
  os_event_t no_flush_event;    /* this event is in the reset state
                                when a flush or a write is running;
                                a thread should wait for this without
                                owning the log mutex, but NOTE that
                                to set or reset this event, the
                                thread MUST own the log mutex! */
  ibool one_flushed;            /* during a flush, this is first FALSE
                                and becomes TRUE when one log group
                                has been written or flushed */
  os_event_t one_flushed_event; /* this event is reset when the
                              flush or write has not yet completed
                              for any log group; e.g., this means
                              that a transaction has been committed
                              when this is set; a thread should wait
                              for this without owning the log mutex,
                              but NOTE that to set or reset this
                              event, the thread MUST own the log
                              mutex! */
  ulint n_log_ios;              /* number of log i/os initiated thus
                                far */
  ulint n_log_ios_old;          /* number of log i/o's at the
                                previous printout */
  time_t last_printout_time;    /* when log_print was last time
                             called */

  /* Fields involved in checkpoints */
  ulint log_group_capacity; /* capacity of the log group; if
                        the checkpoint age exceeds this, it is
                        a serious error because it is possible
                        we will then overwrite log and spoil
                        crash recovery */
  ulint max_modified_age_async;
  /* when this recommended value for lsn
  - buf_pool_get_oldest_modification()
  is exceeded, we start an asynchronous
  preflush of pool pages */
  ulint max_modified_age_sync;
  /* when this recommended value for lsn
  - buf_pool_get_oldest_modification()
  is exceeded, we start a synchronous
  preflush of pool pages */
  ulint adm_checkpoint_interval;
  /* administrator-specified checkpoint
  interval in terms of log growth in
  bytes; the interval actually used by
  the database can be smaller */
  ulint max_checkpoint_age_async;
  /* when this checkpoint age is exceeded
  we start an asynchronous writing of a
  new checkpoint */
  ulint max_checkpoint_age;
  /* this is the maximum allowed value
  for lsn - last_checkpoint_lsn when a
  new query step is started */
  dulint next_checkpoint_no;
  /* next checkpoint number */
  dulint last_checkpoint_lsn;
  /* latest checkpoint lsn */
  dulint next_checkpoint_lsn;
  /* next checkpoint lsn */
  ulint n_pending_checkpoint_writes;
  /* number of currently pending
  checkpoint writes */
  rw_lock_t checkpoint_lock; /* this latch is x-locked when a
                             checkpoint write is running; a thread
                             should wait for this without owning
                             the log mutex */
  byte *checkpoint_buf;      /* checkpoint header is read to this
                             buffer */
  /* Fields involved in archiving */
  ulint archiving_state; /* LOG_ARCH_ON, LOG_ARCH_STOPPING
                         LOG_ARCH_STOPPED, LOG_ARCH_OFF */
  dulint archived_lsn;   /* archiving has advanced to this
                         lsn */
  ulint max_archived_lsn_age_async;
  /* recommended maximum age of
  archived_lsn, before we start
  asynchronous copying to the archive */
  ulint max_archived_lsn_age;
  /* maximum allowed age for
  archived_lsn */
  dulint next_archived_lsn; /* during an archive write,
                          until the write is completed, we
                          store the next value for
                          archived_lsn here: the write
                          completion function then sets the new
                          value to archived_lsn */
  ulint archiving_phase;    /* LOG_ARCHIVE_READ or
                            LOG_ARCHIVE_WRITE */
  ulint n_pending_archive_ios;
  /* number of currently pending reads
  or writes in archiving */
  rw_lock_t archive_lock;  /* this latch is x-locked when an
                           archive write is running; a thread
                           should wait for this without owning
                           the log mutex */
  ulint archive_buf_size;  /* size of archive_buf */
  byte *archive_buf;       /* log segment is written to the
                           archive from this buffer */
  os_event_t archiving_on; /* if archiving has been stopped,
                           a thread can wait for this event to
                           become signaled */
};

#define LOG_ARCH_ON 71
#define LOG_ARCH_STOPPING 72
#define LOG_ARCH_STOPPING2 73
#define LOG_ARCH_STOPPED 74
#define LOG_ARCH_OFF 75

#ifndef UNIV_NONINL
#include "log0log.ic"
#endif

#endif
